Bicycle chain rings

ABSTRACT

A bicycle chain ring, including an inner edge fully circumscribing both an opening and an axis of rotation; an inner surface extending between the inner edge and an outer edge where a plurality of chain ring teeth emanate; and a plurality of ramps disposed about the inner surface, wherein at least one of the plurality of ramps has a lifting surface configured to concurrently engage at least one link of a bicycle chain at two or more distinct pivot points along the length of the chain link to initiate stable lift of the bicycle chain without assistance from any of the plurality of chain ring teeth; wherein the lifting surface has a first end proximate the inner edge and a second end proximate the outer edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/620,274 filed Jun. 12, 2017 which is a continuation of Ser. No.14/144,329 filed Dec. 30, 2013, which is a continuation-in-part of U.S.patent application Ser. No. 11/397,234, which issued as U.S. Pat. No.8,617,015 on Dec. 31, 2013, and which in turn claims priority to U.S.Provisional Patent Application No. 60/721,414, filed Sep. 27, 2005. Thepresent application hereby expressly incorporates by reference thecomplete disclosure of each of these applications in their entities.

BACKGROUND OF THE INVENTION

The present invention relates generally to bicycle cranksets and chainrings. More particularly, this invention relates to bicycle chain ringswith selectively placed ramps and chamfering for improved shiftingperformance.

Conventional bicycle gear systems typically include a crankset includingtwo or three chain rings affixed to a crank arm spider and a separatesimple crank arm. The crank arms of a crankset are configured to receivepedals on one end and to be affixed at the other end to a bottom bracketspindle with bearings for rotation. Conventional bicycle gear systemsalso typically include a rear cog set, occasionally referred to as acassette or cluster having one or more gears with teeth configured torotate a rear wheel through a hub with bearing mechanism. Conventionalbicycle gear systems further include a bicycle chain which is driven bythe chain rings of the crankset which, in turn, drive the cogs of therear cog set. The gears of the bicycle may be selectively changed usingshifters with control wires attached to front and rear derailleurs.

Conventional front derailleurs used with cranksets having two or threechain rings push the chain from one ring to the next using lateralmotion. During an up-shift, for example, the chain guide of a frontderailleur pushes laterally against the side of a chain until the linksof the chain finally catch on a tooth of the larger adjacent chain ringand all subsequent links of the chain follow until the chain is alignedwith the teeth of the larger adjacent chain ring. A down-shift isachieved by pushing laterally against the chain resting on the largerchain ring until the chain can fall down to the smaller chain ring.

This conventional method of pushing laterally against the chain with achain guide provides adequate shifting for most purposes. However, underextreme loading, such as sprinting in the context of racing or out ofthe saddle climbing, there is a need for quicker shifting, especiallyup-shifting. A number of solutions have been proposed to improveshifting performance of a front derailleur.

The inventor of the present application has disclosed an improved frontderailleur, see e.g., U.S. Pat. Nos. 6,454,671 and 7,025,698, both toWickliffe, that solves part of the shifting problem by using a chainguide that physically lifts up the bicycle chain during up-shifts andpulls down the bicycle chain during down-shifts, unlike conventionalfront derailleurs with their predominantly lateral movement of thebicycle chain, during both up- and down-shifts.

Other approaches to improving front derailleur shifting performance havefocused on redesigning bicycle chains by shaping outer chain links tomore readily grab conventional teeth found on conventional chain rings.By shaping outer chain links of a bicycle chain to bow out laterally orto have chamfered or tapered inner surfaces, such chains may be able tograb chain ring teeth quicker.

Still other approaches to improving front derailleur shiftingperformance have focused on redesigning the chain rings themselves. Forexample, U.S. Pat. No. 5,078,653 to Nagano discloses a larger chain ringwith selected teeth having reduced height relative to adjacent teeth,i.e., the crests of the selected teeth having been uniformly cut off toreduce height. Additionally, a short pin has been inserted into theinside of the larger chain ring just below the trimmed teeth and opposedto the smaller chain ring. The arrangement disclosed in the '653 patent,facilitates quicker down-shifts by allowing the chain to disengage atthe trimmed teeth and be lowered onto the teeth of a smaller chain ringvia the short pin. However, there is no indication that the inventiondisclosed in the '653 patent improves up-shifting, especially duringhigh loads as mentioned above.

U.S. Pat. No. 6,666,786 to Yahata discloses another improvement todown-shifting performance through the use of chamfered chain ring teeth.However, neither the '653 patent nor the '786 patent appear to address,let alone solve, the problem of achieving improved up-shifting.

An approach directed toward improving up-shifting by redesigning aconventional chain ring is disclosed in U.S. Pat. No. 5,413,534 toNagano. Another approach to improving up-shifting by redesigning thechain rings is disclosed in U.S. Pat. No. 6,572,500 to Tetsuka. The '534and the '500 patents disclose the use of pins or a pin in combinationwith a tooth and/or tooth chamfering to aid in up-shifting. However, inboth patents the pin or teeth engage a given chain link at the pointdirectly between chain link rollers. The load points of a bicycle chainare at each of the chain link rollers (bushings surrounding pins). Thus,the use of pins as disclosed in the '534 and '500 patents to Nagano andTetsuka, respectively, may increase stress on the chain especiallyduring high loads and, thus, could lead to increased wear and reducelongevity of the chain.

U.S. Pat. No. 5,876,296 to Hsu et al. discloses the use of an axiallyoriented recess in combination with a support protrusion to aid inup-shifting. U.S. Pat. No. 5,738,603 to Schmidt et al. discloses a chainring with pins, chamfered teeth and missing teeth to aid in shifting.Neither of these patents appears to address the added stress to thechain from the allegedly improved up-shifting performance of theirrespective inventions.

Accordingly, there still exists a need in the art for a bicycle chainring that achieves improved shifting performance without increasing thestress on the bicycle chain, thereby addressing at least some of theshortcomings of the prior art.

SUMMARY OF THE INVENTION

An embodiment of a bicycle chain ring is disclosed. The bicycle chainring may include a plurality of ramps disposed about an inner surface ofthe bicycle chain ring, wherein each of the plurality of ramps isconfigured with a lifting surface to engage a plurality of outer chainlinks of a bicycle chain during an up-shift. Additional features ofother embodiments of a bicycle chain ring include, inside tapersadjacent lifting surfaces of the ramps, inside and outside bevels alongtips of teeth to form angled knife edges, outside tapers or notches toselected teeth, partially cutoff teeth and channels between ramps.

An embodiment of a method for up-shifting a bicycle chain from a smallerbicycle chain ring to a larger bicycle chain ring is also disclosed. Themethod may include providing a larger bicycle chain ring having thefeatures described herein. The method may further include rotating acrankset including the smaller and larger bicycle chain rings in aforward motion direction. The method may further include urging thebicycle chain toward the inner surface of the larger bicycle chain ring.The method may further include multiple outer chain links of the bicyclechain engaging a lifting surface on a ramp and lifting the bicycle chainoff of the smaller bicycle chain ring and onto the larger bicycle chainring.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following drawings illustrate exemplary embodiments for carrying outthe invention. Like reference numerals refer to like parts in differentviews or embodiments of the present invention in the drawings.

FIG. 1 is a plan view of an inner surface of a bicycle chain ringaccording to an embodiment of the present invention.

FIG. 2 is an edge view of a portion of a conventional bicycle chain ringviewed from above the teeth.

FIG. 3 is an edge view of a portion of an embodiment of a bicycle chainring according to the present invention.

FIG. 4 is a plan view of the inside of another embodiment of a bicyclechain ring having 44 teeth configured for a standard 104 mm 4-boltcrankset according to the present invention.

FIG. 5 is a plan view of the outside of the embodiment of the bicyclechain ring shown in FIG. 4.

FIG. 6 is an enlarged perspective view of a portion of the inside of thebicycle chain ring shown in FIG. 4.

FIG. 7 is a plan view of the inside of yet another embodiment of abicycle chain ring having 32 contoured teeth configured for a standard104 mm 4-bolt crankset according to the present invention.

FIG. 8 is a plan view of the outside of the embodiment of the bicyclechain ring shown in FIG. 7.

FIG. 9 is an enlarged perspective view of a portion of the inside of thebicycle chain ring shown in FIG. 7.

FIG. 10 is a flow chart of an embodiment of a method for up-shifting abicycle chain from a smaller bicycle chain ring to a larger bicyclechain ring.

FIG. 11 is a plan view of the inside of a 32 tooth bicycle chain ring on94 mm mounting bolt centers having five mounting bolt holes according toan embodiment of the present invention.

FIG. 12 is an enlarged perspective view of a portion of the inside ofthe bicycle chain ring shown in FIG. 11.

FIG. 13 is a super-enlarged perspective view of a portion of the insideof the bicycle chain ring shown in FIG. 11-12.

FIGS. 14-15 are enlarged perspective views of the outside of the bicyclechain ring shown in FIG. 11-13.

FIG. 16 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 17 is a plan view of an embodiment of a 32 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 18 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 19 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 20 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 21 is a plan view of an embodiment of a 34 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 22 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 23 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 24 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 25 is a plan view of an embodiment of a 44 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 26 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 27 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 28 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 29 is a plan view of an embodiment of a 46 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention include chain rings for bicycleshaving specially shaped ramps, tapers and profiled teeth for improvedshifting. The embodiments of the chain rings of the present inventionmay be retrofitted to existing bicycle cranksets and can be configuredfor any standard bolt on configuration and number of teeth. For exampleand not by way of limitation, the embodiments of chain rings of thepresent invention may include middle chain rings in 32 tooth “compact”or 34 tooth “standard” configurations with either four or five boltmounting structures. Additionally, the embodiments of chain rings of thepresent invention may include outer (large or big) chain rings in 44tooth “compact” or 46 tooth “standard” configurations with either fouror five bolt mounting structures. In road bike configurations (dualchain ring or “double crankset”), the embodiments of chain rings of thepresent invention may include outer (big) chain rings in 53 tooth“standard” configurations with five bolt mounting structures. Of course,any number of teeth or bolt patterns may be used with the chain rings ofthe present invention and all such variations are considered to bewithin the scope of the present invention.

An embodiment of a bicycle chain ring is disclosed. The bicycle chainring may include a plurality of ramps disposed about an inner surface ofthe bicycle chain ring, wherein each of the plurality of ramps isconfigured with a lifting surface to engage a plurality of outer chainlinks of a bicycle chain during an up-shift. Lifting surfaces on each ofthe ramps may include linear, bilinear, multilinear, or curved profilesaccording to various embodiments of the bicycle chain ring. The rampsend at a trough or recess between two adjacent teeth according toanother embodiment of the present invention. Furthermore, one of the twoadjacent teeth may be partially cutoff, according to yet anotherembodiment of the present invention.

Another embodiment of a bicycle chain ring may include an inside taperin the bicycle chain ring. The inside taper may be located adjacent toeach of the plurality of ramps. The inside taper may provide decreasingbicycle chain ring thickness in a direction opposite normal rotation(forward motion) of the bicycle chain ring during an up-shift. Accordingto another embodiment, the bicycle chain ring may further includepartially cutoff teeth located radially outward from an outer end ofeach of the plurality of ramps. According to another embodiment, thebicycle chain ring may further include a plurality of non-partiallycutoff teeth in between each of the partially cutoff teeth. According toa further embodiment, each non-partially cutoff tooth may have an insidebevel located proximate its tip. According to a still furtherembodiment, the bicycle chain ring may further include outside bevelslocated in tips of all teeth except for the partially cutoff teeth.

Another embodiment of a bicycle chain ring may further include anoutside taper in each tooth immediately adjacent to and in a clockwisedirection from a partially cutoff tooth when viewing an inside surfaceof the bicycle chain ring, see FIGS. 5 and 8 and related discussion,below. Still another embodiment of a bicycle chain ring may furtherinclude angled knife edges in each non-partially cutoff tooth whenviewed from an edge of the bicycle chain ring looking down onto tips ofthe non-partially cutoff teeth, wherein the angled knife edges are notparallel to a plane running through the bicycle chain ring, see FIG. 3and related discussion below. In yet another embodiment of a bicyclechain ring, a channel may be formed in the inside surface of the bicyclechain ring between adjacent ramps.

Embodiments of bicycle chain rings according to the present inventionmay have any suitable number of teeth, but more particularly in therange from 30 to 54 teeth. Embodiments of bicycle chain rings accordingto the present invention may have four or five support structures eachhaving a mounting hole configured for attachment to a crank arm spider.

Embodiments of bicycle chain rings according to the present inventionmay include ramp structural width ranging from about 2 mm to about 30mm. Ramp structural width may be measured in parallel to an insidesurface of the bicycle chain ring and perpendicular to a lifting surfaceof the ramp. Embodiments of bicycle chain rings according to the presentinvention may include ramp structural thickness ranging from about 2 mmto about 5 mm. Ramp structural thickness may be measured perpendicularfrom the inside surface of the bicycle chain ring to the top surface ofa ramp.

FIG. 1 is a plan view of an inner surface of a bicycle chain ring 100according to an embodiment of the present invention. The bicycle chainring 100 may include a circular structural member 102 having a pluralityof contoured teeth 150A-D replicated serially in a clockwise mannerabout a circumference of the circular structural member 102. The bicyclechain ring 100 may further include a plurality of ramps 108 that areraised up from, and regularly disposed about, the inner surface ofcircular structural member 102.

Each of the plurality of ramps 108 may be configured with a liftingsurface 110 to engage a plurality of outer chain links of a bicyclechain (not shown) to aid in lifting the bicycle chain from a smallerchain ring (also not shown) that is concentric but displaced away fromthe inner surface of bicycle chain ring 100. Each lifting surface 110 ofeach ramp 108 may run generally from a periphery 112 of an inner opening120 to an outer end 122 near the base of a partially cutoff tooth 150Das shown in the illustrated embodiment of bicycle chain ring 100.However, lifting surfaces 110 need not extend all the way to theperiphery 112 of inner opening 120, for example, see ramp starts 128.

According to an embodiment of the present invention, lifting surfaces110 may be linear in profile as shown in FIG. 1. Alternatively,according to another embodiment of bicycle chain ring 400 of the presentinvention, at least one of the lifting surfaces may be multi-linear inprofile (e.g., see 410 in FIG. 4). According to still another embodimentof bicycle chain ring 100 of the present invention, at least one of thelifting surfaces 110 may be arcuate or curved in profile, not shown inFIGS.

According to an embodiment of a bicycle chain ring 100 shown in FIG. 1,each of the plurality of ramps 108 may begin near a support structure104 or at a periphery of an inner opening 112 of the circular structuralmember 102. Each of the plurality of ramps 108 ends at a trough orrecess 114 between teeth 150A and 150D. The thickness and width of thestructure used to form the plurality of ramps 108 may be of any suitabledimension. Furthermore, any suitable material may be used to form thechain rings 100 according to embodiments of the present invention, forexample and not by way of limitation, aluminum, titanium, steel andcarbon fiber.

According to another embodiment of the present invention, bicycle chainring 100 may further include an inside taper 116 in the circularstructural member 102 located above each of the plurality of ramps 108.The inside taper 116 may be achieved by any suitable means including,but not limited to machining, stamping or investment casting. The insidetaper 116 may be linear in nature and reduce the thickness of thecircular structural member 102 above each ramp 108 in any amount rangingfrom 0 mm to approximately 2 mm. The inside taper 116 may begin, forexample along the curved lines 117 and extend through teeth 150C and150D to an outer end 122 where the taper is greatest. The inside taper116 provides decreasing circular structural member 102 thickness in adirection opposite normal rotation, R, of the bicycle chain ring 100during an up-shift. See FIG. 3 and related discussion below for furtherillustration of inside taper 116.

According to still another embodiment of the present invention, bicyclechain ring 100 may further include partially cutoff teeth 150D locatedradially above an outer end 122 of each of the plurality of ramps 108.Nonpartially cutoff teeth 150A-C may be found between the partiallycutoff teeth 150D. Generally speaking, all teeth 150A-D shown in FIG. 1are contoured or profiled to improve shifting characteristics asdescribed herein.

FIG. 2 is an edge view of a portion of a conventional bicycle chainring, shown generally at 200, viewed from above the teeth 250. Therelative dimensions of FIG. 2 are not drawn to scale, but, areexaggerated for ease of explanation. A conventional bicycle chain ring200 may have an inside surface 240 and an outside surface 242. Aconventional bicycle chain ring 200 may have generally uniform shapedteeth 250 having knife edge points 234 separated by generally uniformlyrounded troughs 236 that support round bushings (not shown) of a bicyclechain (not shown). Conventional bicycle chain rings 200 may also have anouter ridge 238 and/or an inner ridge (not shown) for structuralsupport. FIG. 2 also illustrates a center plane 270 (see dotted line)that is coplanar with knife edge points 234.

In contrast, FIG. 3 is an edge view of a portion of an embodiment of abicycle chain ring 300 according to the present invention (as indicatedon FIG. 1 by bent arrows 3). As with FIG. 2, the relative dimensions ofFIG. 3 are not drawn to scale, but are exaggerated for ease ofexplanation. The view of a portion of bicycle chain ring 300 shown inFIG. 3 illustrates a top view of four adjacent contoured teeth 350A-D.Bicycle chain ring 300 may also have an outer ridge 338, according tothe embodiment shown in FIG. 3. Bicycle chain ring 300 may furtherinclude rounded troughs 336 for supporting cylindrical bushings (notshown) of a bicycle chain (not shown) in between each of the contouredteeth 350A-D. However, the surfaces of rounded troughs 336 are notuniform like the rounded troughs 236 of the conventional bicycle chainring 200 (FIG. 2) because of the additional novel features of thecontoured teeth 350A-D.

The portion of an embodiment of a bicycle chain ring 300 illustrates aramp 308 having a lifting surface 310 for engaging a bicycle chain (notshown) during up-shifts. The ramp 308 with lifting surface 310 is aunique feature that is completely missing from conventional bicyclechain ring 200. While some conventional bicycle chain rings have pins,they still do not have ramps 308 with extended lifting surfaces forengaging multiple links of a bicycle chain. The pins associated withsome conventional bicycle chain rings only engage a single bicycle chainlink. However, the inside lifting surfaces 110 and 310 of ramps 108 and308 of the embodiments of bicycle chain rings 100 and 300 of the presentinvention are capable of supporting a plurality of bicycle chain links.This feature of embodiments of the present invention provides bettersupport to lift a bicycle chain during up-shifts. This feature isespecially important during hard up-shifts, for example when sprintingor when the rider is out of the saddle during climbing, thereby puttingsubstantial tensile force on the chain.

The lifting surface 310 on ramp 308 is expanded (below the dashed linein FIG. 3) along inside taper 316 (shown generally below bracket in FIG.3). The inside taper 316 is formed in the inside of bicycle chain ring300. The inside taper 316 narrows the overall thickness of the teeth350A-D and troughs (saddles) 336 by a distance, d, defined by a distancemeasured from inside surface 340 (shown in part by dashed line in FIG.3) to the deepest chamfer cut point 352. That inside taper distance, d,may be any amount up to about 2 mm according to various embodiments ofbicycle chain ring 300.

Another feature of bicycle chain ring 300 is the angled knife edges 334of teeth 350A-C. FIG. 3 illustrates a center plane 370 (see dotted line)that clearly shows that the angled knife edges 334 are noncoplanar,i.e., angled knife edges 334 do not fall along the center line 370, butare angled to it. The angling of the knife edges 334 of teeth 350A-Cprovides enhanced bicycle chain meshing during an up-shift because thebicycle chain twists during an up-shift from a smaller to larger chainring. Note that the angling of the knife edges 334 shown in FIG. 3 areexaggerated for ease of explanation and may not actually be angled asgreatly as illustrated. The angling of the knife edges 334 tracks thetwisting of the bicycle chain to more quickly engage the bicycle chainthan without the angled knife edges 334. This feature improvesup-shifting performance (faster) relative to knife edges points 234 (seeFIG. 2) having no angling. This feature may also improve chain meshingwhen the bicycle chain is being driven at an angle relative to rear cogsassociated with a freewheel or cassette mechanism. Poor chain meshing ischaracterized by lack of consistent seating of the bicycle chain introughs 236 and may be caused by the bicycle chain being driven at anangle relative to rear cogs. Poor chain meshing may also becharacterized by increased noise resulting from the lack of consistentseating of the bicycle chain and its cylindrical bushings in troughs236.

Still another feature illustrated in FIG. 3 is outside taper 356 incontoured tooth 350A. Outside taper 356 works in conjunction with rampto the right of tooth 350A (not shown) to narrow the thickness ofcontoured tooth 350A and thereby making it easier for tooth 350A to grabthe bicycle chain ring 300 during an up-shift. According to anotherembodiment, outside taper 356 may be a short bevel or chamfer along theoutside edge of tooth 350A rather than the taper along the entire widthof tooth 350A shown in FIG. 3. Note that four contoured teeth 350A-D areshown associated with the ramp 308, in FIG. 3. However, any number ofteeth, three to seven may be associated with each ramp according toother embodiments of the present invention. In those other instances,the tooth having an outside taper would be left of cutoff tooth 350D inthe view of FIG. 3. For example, see outside taper 556 in FIG. 5 andrelated discussion below.

Structural thickness, t, of ramps 308 may range from about 2 mm to about5 mm according to embodiments of the present invention. Structuralthickness, t, less than about 2 mm may not provide enough liftingsurface along the ramp 308 for efficient up-shifting. Structuralthickness, t, greater than about 5 mm may cause the bicycle chain tounnecessarily catch when the chain is tracking in smaller chain ringsand angled in toward the larger chain ring because of rear cogalignment.

Referring to FIGS. 1 and 3, partially cutoff teeth 150D and 350D do nothave a knife edge 334 because the upper portion of teeth 150D and 350Dhave been removed. The purpose for reducing the profile of teeth 150Dand 350D by partially cutting off the upper portion of teeth 150D and350D is to provide a point of lateral entry of the bicycle chain overthe bicycle chain ring 100 and 300 during an up-shift. Thus, thepartially cutoff teeth 150D and 350D encourage lateral movement of thebicycle chain from a small bicycle chain ring onto bicycle chain rings100 and 300. This encouraging of lateral movement improves shiftingperformance over conventional bicycle chain rings such as the oneillustrated in FIG. 2, where all of the teeth 250 are of identicalheight profile. Incidentally, the partially cutoff teeth 150D and 350Dalso improve down-shifting for essentially the same reason: encouraginglateral movement of the bicycle chain. However, during a down-shift, thebicycle chain is urged off of bicycle chain ring 300.

Embodiments of bicycle chain rings 100 and 300 illustrated in FIGS. 1and 3 may have three contoured teeth 150B-D and 350B-D or four contouredteeth 150A-D and 350A-D associated with each ramp 108 and 308. However,other combinations and numbers of contoured teeth 150A-D and 350A-D maybe associated with ramps 108 and 308 consistent with the presentinvention. Such other combinations and numbers of contoured teeth areconsidered to be within the spirit and scope of the present invention.

FIG. 4 is a plan view of the inside of another embodiment of a bicyclechain ring 400 having 44 contoured teeth 450A-D configured for astandard 104 mm 4-bolt crankset according to the present invention.Bicycle chain ring 400 may be used as a large chain ring on a mountainbike crankset. The axis of rotation 133 and the direction of rotation Rare highlighted in FIG. 4. It will be readily apparent to one ofordinary skill in the art that the invention is not limited to anyparticular mounting bolt pattern, mounting bolt number, number of teethor bolt pattern radius.

Contoured teeth 450A-D may include inside bevels 460 along the tips toachieve the angled knife edges (334 in FIG. 3) as a feature of thepresent invention. Inside bevels 460 form portions of the angled knifeedges (334 in FIG. 3) that improve bicycle chain meshing as describedherein. Inside bevels 460 may be of any shape that improves bicyclechain meshing and therefore, reduce noise and improves shiftingperformance relative to bicycle chain rings without such features.

According to the embodiment of bicycle chain ring 400, ramps 408 may belinear profile ramps 408A or bilinear profile ramps 408B. The bilinearprofile ramps 408B may be partially formed on support structures 104,thus allowing for longer ramps and bilinear configurations. Ramps 408A-Bmay include gaps (not shown) according to other embodiments of bicyclechain ring 400, but each ramp 408A-B always supports more than a singlelink as distinguished from pins used in prior art chain rings. FIG. 4also illustrates structural members 104 (four shown) and theirassociated mounting holes 106.

FIG. 4 also illustrates the regions of inside taper 416 adjacent thelifting surface 410 of each ramp 408A-B. Inside taper 416 may take anyform or shape that narrows the thickness of the bicycle chain ring 400above the ramps 408A-B according to various embodiments of the presentinvention. See also FIG. 6 and related discussion below for an enlargedview of inside taper 416. The structural width, w, of any given ramp408A-B may be of any suitable dimension that provides consistent supportof a bicycle chain. Any structural width, w, less than about 2 mm, maylack suitable wear characteristics for use on bicycles over extendedperiods of time. Structural width, w, may vary from among the ramps 408located on a single bicycle chain ring 400 according to otherembodiments of the present invention, e.g., see FIGS. 7 and 9, below.Structural width, w, may fall within the range from about 2 mm to about30 mm according to various embodiments of the present invention.

FIG. 5 is a plan view of the outside of the embodiment of the bicyclechain ring 400 shown in FIG. 4. In the view of FIG. 5 outer ridge 538appears as a circle underneath contoured teeth 450A-D. FIG. 5 alsoillustrates structural members 104 (four shown) and their associatedmounting holes 106. FIG. 5 further illustrates the outside bevel 554 ofcontoured teeth 450, particularly contoured teeth 450A-C and notincluding partially cutoff teeth 450D (i.e., all teeth other than cutoffteeth 450D). Outside bevel 554 provides enhanced bicycle chain meshingas described above. Another feature of bicycle chain ring 400illustrated in FIG. 5 is outside taper 556. Outside taper 556 isassociated with contoured teeth 450A or 450B, depending on the number ofcontoured teeth (three or four) associated with a given ramp 408.Outside taper 556 narrows contoured teeth 450A or 450B at a positionadjacent to cutoff teeth 450D. The outside taper 556 is configured tograb the inside of a bicycle chain link between cylindrical bushings.Thus, outside taper 556 can more quickly grab the bicycle chain (notshown) during an up-shift because the profile of contoured teeth 450A or450B is narrower. Outside taper 556 may also improve chain meshing asdescribed above. Embodiments of outside taper 556 may encompass most ofthe body of contoured teeth 450A or 450B as shown in bicycle chain ring400 of FIG. 5. Alternatively, outside taper 556 may be a smallerchamfer, bevel or notch (not shown in FIG. 5, but see FIG. 8 and outsidenotch 856) on the body of contoured teeth 450A or 450B nearest contouredteeth 450D according to other embodiments of the present invention.

FIG. 6 is a perspective view of a portion of the inside of the bicyclechain ring 400 shown in FIG. 4, enlarged to show detail. The portion ofthe bicycle chain ring 400 shown in FIG. 6 includes two ramps 408, morespecifically a linear profile ramp 408A and a bilinear profiled ramp408B. FIG. 6 also highlights the FIG. 6 also illustrates a supportstructure 104, a mounting hole 106, a lifting surface 410 on each ramp408A-B, contoured teeth 450A-D, inside bevels 460 associated withcontoured teeth 450A-C and inside taper 416 adjacent ramps 408A-B. FIG.6 further illustrates a channel 670 that is formed between adjacentramps 408A-B on the inside surface of bicycle chain ring 400 accordingto the present invention. Channel 670 provides a space for the bicyclechain during up-shifts. The lifting surface 410 shown in FIG. 6 has afirst width at a first point 471 located adjacent to the inner edge 472or inner periphery. At a second point 473, the lifting surface has asecond width that is greater than the first width. The first point 471and second point 473 are located distant from each other and configuredto simultaneously striking two distinct portions of a bicycle chain whenthe lifting surface first acts upon the chain. The ramps 408 alsoinclude disengagement surfaces 474 that are located near the teeth 460.The planar disengagement surfaces 474 are adjacent to and perpendicularto the inner surface of the chain ring as well as being adjacent to thelifting surfaces 410.

FIG. 7 is a plan view of the inside of yet another embodiment of abicycle chain ring 700 having 32 contoured teeth 750A-D configured for astandard 104 mm 4-bolt crankset according to the present invention.Bicycle chain ring 700 may be configured as a middle chain ring on amountain bike crankset Bicycle chain rings 400 and 700 together may forma compact set of chain rings for a mountain bike crankset Bicycle chainring 700 may include a circular structural member 702, a plurality ofsupport structures 704 (four shown), each with mounting holes 106 (fourshown). Bicycle chain ring 700 may further include ramps 708A-B (eighttotal: four ramps 708A and four ramps 708B) of various widths, w,depending on the location of the ramp 708A-B. For example and not by wayof limitation, ramp 708A may include relatively narrow width, w1.Whereas ramp 708B may have a relatively wide width, w2, that encompassesmounting hole 106, as shown in FIG. 7. As noted above, ramp structuralwidth, w, w1 or w2, may be anywhere in the range from about 2 mm toabout 30 mm. Structural thickness (not shown in FIG. 7) of ramps 708A-Bmay be as described above for the embodiment of bicycle chain ring 300in FIG. 3.

Referring again to FIG. 7, each ramp 708A-B is configured with a liftingsurface 710. Each ramp 708A-B may be associated with three or fivecontoured teeth 750A-E depending on the size and location of theassociated ramp 708A-B. Partially cutoff teeth 750E are separated bynonpartially cutoff, contoured teeth 750A-D. Of course, contoured teeth750A-E shown in the embodiment of FIG. 7, may have similar features andcharacteristics to contoured teeth 150A-D, 350A-D and 450A-D, as otherembodiments described above. Bicycle chain ring 700 may further haveinside tapers 716 adjacent the lifting surfaces 710 of each ramp 708A-B.Inside tapers 716 may have similar features and characteristics toinside tapers 116 (FIG. 1) and 316 (FIG. 3) described above. FIG. 7 alsoillustrates support structures 704 and associated mounting holes 106.

FIG. 8 is a plan view of the outside of the embodiment of the bicyclechain ring 700 shown in FIG. 7. In the view of FIG. 8, outer ridge 838appears as a circle underneath contoured teeth 750A-E. FIG. 8 alsoillustrates the outside bevel 854 of contoured teeth 750, particularlycontoured teeth 750A-D and not including partially cutoff teeth 750E(i.e., all teeth other than cutoff teeth 750E). Outside bevel 854provides enhanced bicycle chain meshing as described above. FIG. 8 alsoillustrates outside notch 856. Outside notch 856 is associated withcontoured teeth 750A or 750C depending on the number of contoured teeth(three or five) associated with a given ramp 708 (not shown in FIG. 8).Outside notch 856 narrows contoured teeth 750A or 750C at a positionadjacent to cutoff teeth 750E. The outside notch 856 is configured tograb the inside of a bicycle chain link between cylindrical bushings(not shown) in the chain (also not shown). Thus, outside notch 856 canmore quickly engage the bicycle chain (not shown) during an up-shift,because the profile of contoured teeth 750A or 750C is narrower. Outsidenotch 856 may also improve chain meshing as described above. Otherembodiments of outside notch 856 may encompass most of the body ofcontoured teeth 750A or 750C as shown in outside taper 556 of bicyclechain ring 400 of FIG. 5. FIG. 8 also illustrates support structures 704and associated mounting holes 106.

Referring now to FIG. 9, a perspective view of a portion of the insideof the bicycle chain ring 700 of FIG. 7 is enlarged to show detail. Theportion of the bicycle chain ring 700 shown in FIG. 9 includes twolinear ramps 708A-B, more specifically a narrow width (w1) linearprofile ramp 708A and a wide width (w2) linear profiled ramp 708B (seealso FIG. 7). FIG. 9 also illustrates a support structure 704, amounting hole 106, a lifting surface 710 on each ramp 708A-B, contouredteeth 750A-E and inside taper 716 adjacent ramps 708A-B. FIG. 9 furtherillustrates a channel 970 that is formed between adjacent ramps 708A-Bon the inside surface of bicycle chain ring 700 according to the presentinvention. Channel 970 provides a space for the bicycle chain duringup-shifts.

Referring generally to FIGS. 1 and 3-7, embodiments of bicycle chainrings, 100, 300, 400 and 700 include between two and five nonpartiallycutoff, contoured teeth 150A-C, 350A-C, 450A-C and 750A-D (see FIG. 11,below for an example of five nonpartially cutoff teeth) separating anytwo nearest cutoff teeth 150D, 350D, 450D and 750E. The centers ofmounting holes 106 may be on the circumference of a circle 104 mm indiameter according to a particular embodiment of the bicycle chain ringsof the present invention. According to alternative embodiments, centersof mounting holes 106 may be on the circumference of a circle 94 mm or110 mm in diameter. The bicycle chain rings 100, 300, 400 and 700disclosed herein may be configured for compatibility with anycommercially available crankset, for example and not by way oflimitation, cranksets manufactured by Shimano™, Campagnolo™, Race Face™Truvative™, Richey™, Nashbar™, FSA™, and any other manufacturer or modelof crankset.

Yet another feature of the partially cutoff teeth 150D, 350D, 450D and750E disclosed herein is the angle, θ, at which such teeth are cutoff.Referring specifically to FIG. 7, note that angle, θ, is shown asmeasured from tangential line, l1, to angled line, l2, traced throughthe top of partially cutoff teeth 750E. By partially cutting off teeth750E at angle, θ, the bicycle chain is given clearance it needs during adown-shift to be able to move laterally past the partially cutoff tooth750E and drop off chain ring 700 to engage the next smaller chain ring(not shown). During a down-shift, the partially cutoff tooth 750E allowsan entire chain link to move laterally towards the inside of bicyclechain ring 700 and past the partially cutoff tooth 750E without makingcontact with tooth 750E. This feature promotes faster down-shifts. Theangled (θ) cutoff teeth 750E are preferred to tangentially cutoff teethof the prior art (see e.g., U.S. Pat. No. 5,078,653 to Nagano asdiscussed above in the background) because the bicycle chain comes offof chain ring 700 at an angle approximated by angle, θ, nottangentially, during a down-shift.

FIG. 10 is a flow chart of an embodiment of a method 1000 forup-shifting a bicycle chain from a smaller bicycle chain ring to alarger bicycle chain ring. Method 1000 may include providing 1002 alarger bicycle chain ring as described herein. Method 1000 may furtherinclude rotating 1004 a crankset including the smaller and largerbicycle chain rings in a forward motion direction. Method 1000 mayfurther include urging 1006 the bicycle chain toward the inner surfaceor side of the larger bicycle chain ring. This urging 1006 may beachieved by activating a front derailleur having a chain guide thatpushes laterally against the sides of a bicycle chain. Alternatively,urging 1006 may be achieved by activating a front derailleur such asthose described in U.S. Pat. No. 6,454,671 and U.S. Published PatentApplication No. US20020177498, both to the present inventor, ChristopherA. Wickliffe, thereby lifting a lower outside corner of a bicycle chaintoward the larger bicycle chain ring. Method 1000 may further includemultiple outer chain links of the bicycle chain engaging 1008 a liftingsurface on a ramp and lifting 1010 the bicycle chain off of the smallerbicycle chain ring and onto the larger bicycle chain ring.

Additional embodiments of bicycle chain rings according to the presentinvention are shown in FIGS. 11-29. FIG. 11 is a plan view of the insideof a 32 tooth bicycle chain ring 1100 on 94 mm mounting bolt centershaving five mounting bolt holes according to an embodiment of thepresent invention. FIG. 12 is an enlarged perspective view of a portionof the inside of the bicycle chain ring 1100 shown in FIG. 11. FIG. 12provides an enlarged illustration of mounting hole 106, ramps 1108A and1108B, and inside taper 1116 associated with this embodiment of abicycle chain ring 1100. The ramp 1108A includes a lifting surface witha concave portion 1117 adjacent to the inner edge FIG. 13 is asuper-enlarged perspective view of a portion of the inside of thebicycle chain ring 1100 shown in FIG. 11-12. FIG. 13 illustrates insidetaper 1116, mounting hole 106 and ramp 1108A. FIG. 13 also illustrates aseamless transition 1123 between the inner side of the ring and theinwardly extending surface. The inwardly extending surface includes aportion that is flush with the edge. The concave portion highlighted inFIG. 12 includes a portion that is flush with the inner edge (see alsoFIG. 11).

FIGS. 14-15 are enlarged perspective views of the outside of the bicyclechain ring 1100 shown in FIG. 11-13. FIGS. 14-15 shows an enlargedperspective view of outer ridge 1138, outside bevels 1154 and outsidenotch 1156. FIG. 15 also shows mounting hole 106 and an obstructed viewof inside taper 1116.

It is important to note that the ramps 108, 308, 408A-B, 708A-B and1108A-B, on the inside surface of the bicycle chain rings 100, 300, 400,700 and 1100 disclosed herein, contact and lift the bicycle chaindirectly underneath the load points, i.e., chain link rollers (bushingsand pins), of multiple chain links during an up-shift. Each ramp engagesthe bicycle chain directly below the chain link rollers and lifts atmultiple load points (below each chain link roller). This is in distinctcontrast to conventional bicycle chain rings with pins that attempt toaccomplish the same task. Such conventional pin lifting is necessarilyat a single load point (between two chain link rollers) to accomplishthe bicycle chain lifting. Thus, the ramps 108, 308, 408A-B, 708A-B and1108A-B, of the present invention spread the load over multiple loadpoints.

FIG. 16 is a plan view of an embodiment of a 34-tooth bicycle chain ringon 104 mm mounting bolt centers 1600 having four mounting holes 1602according to an embodiment of the present invention. FIG. 17 is a planview of an embodiment of a 32-tooth bicycle chain ring 1700 compatiblewith a four mounting hole-Shimano™ XTR™ crankset (not shown) accordingto an embodiment of the present invention. Chain ring 1700 includes 4mounting holes 1702. FIG. 18 is a plan view of an embodiment of a34-tooth bicycle chain ring on 94 mm mounting bolt centers 1800 havingfive mounting holes 1802 according to an embodiment of the presentinvention. FIG. 19 is a plan view of an embodiment of a 34-tooth bicyclechain ring on 104 mm mounting bolt centers 1900 having four mountingholes 1902 according to an embodiment of the present invention. FIG. 20is a plan view of an embodiment of a 34-tooth bicycle chain ring on 110mm mounting bolt centers 2000 having five mounting holes 2002 accordingto an embodiment of the present invention. FIG. 21 is a plan view of anembodiment of a 34-tooth bicycle chain ring 2100 compatible with a fourmounting hole Shimano™ XTR™ crankset (not shown) according to anembodiment of the present invention. Chain ring 2100 includes fourmounting holes 2102. FIG. 22 is a plan view of an embodiment of a44-tooth bicycle chain ring on 94 mm mounting bolt centers 2200 havingfive mounting holes 2202 according to an embodiment of the presentinvention. FIG. 23 is a plan view of an embodiment of a 44-tooth bicyclechain ring on 104 mm mounting bolt centers 2300 having four mountingholes 2302 according to an embodiment of the present invention. FIG. 24is a plan view of an embodiment of a 44-tooth bicycle chain ring on 110mm mounting bolt centers 2400 having five mounting holes 2402 accordingto an embodiment of the present invention. FIG. 25 is a plan view of anembodiment of a 44-tooth bicycle chain ring 2500 compatible with a fourmounting hole Shimano™ XTR™ crankset (not shown) according to anembodiment of the present invention. Chain ring 2500 includes fourmounting holes 2502. FIG. 26 is a plan view of an embodiment of a46-tooth bicycle chain ring on 94 mm mounting bolt centers 2600 havingfive mounting holes 2602 according to an embodiment of the presentinvention. FIG. 27 is a plan view of an embodiment of a 46-tooth bicyclechain ring on 104 mm mounting bolt centers 2700 having four mountingholes 2702 according to an embodiment of the present invention. FIG. 28is a plan view of an embodiment of a 46-tooth bicycle chain ring on 110mm mounting bolt centers 2800 having five mounting holes 2802 accordingto an embodiment of the present invention. FIG. 29 is a plan view of anembodiment of a 46-tooth bicycle chain ring 2900 compatible with a fourmounting hole Shimano™ XTR™ crankset (not shown) according to anembodiment of the present invention. Chain ring 2900 includes fourmounting holes 2902. Chain ring 2900 further includes twelve ramps 2908having a leading edge 2930 that is curved in profile. Thus, ramps 2908have both a linear profile and a curved profile on the leading edge2930.

While the foregoing advantages of the present invention are manifestedin the illustrated embodiments of the invention, a variety of changescan be made to the configuration, design and construction of theinvention to achieve those advantages. Hence, reference herein tospecific details of the structure and function of the present inventionis by way of example only and not by way of limitation.

The invention claimed is:
 1. A bicycle chain ring, comprising: an inneredge fully circumscribing both an opening and an axis of rotation; aninner surface extending between the inner edge and an outer edge where aplurality of chain ring teeth emanate; and a plurality of ramps disposedabout the inner surface, wherein at least one of the plurality of rampshas a lifting surface configured to concurrently engage at least onelink of a bicycle chain at two or more distinct pivot points along thelength of the chain link on a substantially linear portion of thelifting surface to initiate stable lift of the bicycle chain withoutassistance from any of the plurality of chain ring teeth.
 2. The bicyclechain ring of claim 1, wherein a second end of the lifting surfaceterminates before reaching the bottom of a trough positioned between twoor more of the plurality of chain ring teeth.
 3. The bicycle chain ringaccording to claim 1, wherein the lifting surface comprises an insidetaper in the inner surface of the bicycle chain ring, the inside taperconfigured to receive and lift the at least a portion of one link of abicycle chain during an up-shift.
 4. The bicycle chain ring according toclaim 3, wherein the inside taper comprises a profile having a linearportion when viewed perpendicular to the inner surface of the bicyclechain ring.
 5. The bicycle chain ring according to claim 3, wherein theinside taper comprises a profile having at least one curved portion whenviewed perpendicular to the inner surface of the bicycle chain ring. 6.The bicycle chain ring according to claim 3, wherein the inside tapercomprises a profile having a linear portion and a curved portion whenviewed perpendicular to the inner surface of the bicycle chain ring. 7.The bicycle chain ring according to claim 6, wherein the inside tapercomprises a profile which is configured to receive a single outer linkof a bicycle chain when viewed perpendicular to the inner surface of thebicycle chain ring.
 8. The bicycle chain ring according to claim 3,wherein the lifting surface includes a concave portion adjacent to theinner edge.
 9. The bicycle chain ring according to claim 8, wherein theconcave portion is flush with the inner edge at a first point.
 10. Abicycle chain ring, comprising an inner periphery in a surroundingconfiguration to an axis of rotation; an outer periphery of the chainring where a plurality of chain ring teeth emanate; an inner surfaceextending between the inner periphery and the outer periphery; aplurality of ramps disposed about the inner surface, wherein each of theplurality of ramps includes a lifting surface for initiating lift of abicycle chain; and at least one of the lifting surfaces extendingradially along the inner surface from the inner periphery of the chainring outward toward the outer periphery; wherein the lifting surface ofat least one ramp has a first width at a first location adjacent to theinner periphery, a second width at a second location distant from theinner periphery, wherein the second width is greater than the firstwidth.
 11. The bicycle chain ring of claim 10, wherein the at least oneramp includes a first planar surface near chain ring teeth, the firstplanar surface adjacent to and substantially perpendicular to the innersurface.
 12. The bicycle chain ring of claim 10, wherein at least onelifting surface has a first end proximate the inner periphery and asecond end proximate to the outer periphery.
 13. The bicycle chain ringof claim 12, wherein the second end of the at least one lifting surfaceterminates before reaching the bottom of a trough positioned between twoor more of the plurality of chain ring teeth.
 14. The bicycle chain ringaccording to claim 10, wherein at least one of the lifting surfaces ismulti-linear in profile when viewed along the axis of rotation.
 15. Thebicycle chain ring according to claim 10, wherein at least one of theplurality of ramps has a structural width ranging from 2 mm to 30 mm,the structural width being measured in parallel to an inside surface ofthe bicycle chain ring and perpendicular to the lifting surface of theramp.
 16. The bicycle chain ring according to claim 10, wherein at leastone of the plurality of ramps has a structural thickness ranging from 2mm to 5 mm, the structural thickness being measured perpendicularly froman inside surface of the bicycle chain ring to a top surface of theramp.
 17. The bicycle chain ring according to claim 10, wherein at leastone of the lifting surfaces begins at a first radius as measured fromthe axis of rotation and extends outward to a second radius, the secondradius being greater than the first radius.
 18. The bicycle chain ringaccording to claim 17, wherein the first radius is greater than asmaller adjacent chain ring radius.